The present invention relates to a continuous press including a frame, a driving shaft journaled to the frame at its both ends by means of thrust bearings, a screw drum disposed around the driving shaft to rotate therewith, a screw blade arranged helically around the outer surface of the screw drum, an outer drum arranged around the screw blade and having a number of small filtering holes, an inlet provided in the outer drum for introducing raw materials into a space between the screw drum and outer drum and an outlet provided in the outer drum for discharging the pressed materials as a cake, whereby the space is gradually made smaller in a direction from said inlet to said outlet.
Such a continuous press has been known from, for example U.S. Pat. No. 3,939,763 and can be effectively utilized to press continuously water, oils and fats out of various kinds of raw materials. In the known continuous press, a removable lid member is provided at the outlet of the press for applying a pressure to raw material to adjust the amount of cake discharged from the outlet. However, in the known press, when the amount of cake is increased, the lid is easily opened to a larger extent and thus the lid does not move suitably to regulate the amount of cake. Therefore, it is rather difficult to adjust the pressure applied to the cake to a given constant value. In order to effect the desired pressing operation even under such a condition that the amount of the cake fluctuates largely, it is very important to keep the cake pressure constant. In the known continuous press, a repelling force generated by the pressing is applied to the screw shaft via the screw blade and screw drum and therefore, the thrust bearings are subjected to the very strong thrust force. This requires large and strong thrust bearings, so that the cost is increased. Further, the usuable duration of the thrust bearings becomes short and the bearings must be repaired often. Thus, in the known continuous press the maintenance is very combersome.